1. Field of the Invention
This invention pertains to forced-air ventilation systems for cargo in cargo ships. More particularly, it pertains to a ventilation system which is useful with normal cargo and also, if desired, with containerized cargo. The system can be of either the open-loop or closed-loop type.
2. Review of the Prior Art
Cargo ships having air supply and exhaust duct systems, by which air can be supplied from a ventilation source via individual connections to large-scale cargo containers and by which air can be vented from the containers and led back to the source, are known. In such ships, container guides are located in the hold spaces for accommodating and aligning a number of containers, usually in a series of vertical stacks, adjacent the air supply and exhaust ducts so that separate air supply and exhaust connections can be made to the individual containers from the ducts. In these ships, the ventilation source can include a refrigeration plant coupled to at least some of the air supply ducts so that containers loaded with perishable cargo can be refrigerated during their residence aboard the ship. Other containers with less sensitive cargo can receive unrefrigerated air, and can vent exhaust air to the atmosphere if desired.
The practical disadvantage which exists with cargo ships having such hold-space ventilation arrangements is that the ships are designed exclusively as container ships; the ships are designed to receive only containers of a standardized configuration, which are relatively large. Such container ships have no intermediate decks in the hold spaces. They are designed to support containers in vertical stacks which extend from the vessel innerbottom to hatches located in the weatherdeck of the ship.
If it is desired to transport cargo in other forms, i.e., loose cargo, cargo in separate small containers, cargo in cartons or crates, or cargo on standard pallets, then it is necessary to use other ships which have intermediate or 'tween decks in the hold spaces. These other ships, however, are rarely capable of accommodating standard containers in their holds.
The trend in the maritime industry, world-wide, is toward increased containerization of cargo. Clearly, container-ships have a place and may be ideal in many situations, as in runs between Hawaii and the West Coast of the United States. However, there are many situations where ships of more generalized nature, suited for carrying containers as well as other forms of cargo, have application and are economically more desirable than container-ships.
Thus, a need is seen to exist for cargo ships of generalized nature, capable of carrying both containers and other forms of non-bulk cargo, having improved and innovative ventilation systems which are useful with containers and which also are useful, in a way not heretofore suggested, with cargo in other forms. Such ships would fill a distinct need in the world's marine shipping industry.